Aliasingartefacten

Aliasingartefacten, often shortened to aliasing, are unwanted visual distortions that can appear in digital images and signals. They occur when a signal is sampled at a rate that is too low to accurately represent its original detail. This is a fundamental concept in digital signal processing and computer graphics, often governed by the Nyquist-Shannon sampling theorem.

In the context of images, aliasing commonly manifests as jagged edges, stair-stepping patterns on diagonal lines, or moiré patterns in finely detailed textures. This happens because the sampling points (pixels) are too far apart to capture the smooth transitions of the original high-frequency details. For example, a thin, diagonal line might appear as a series of disconnected dots or steps rather than a continuous line.

In audio signals, aliasing can result in the generation of spurious frequencies that were not present in the original sound. This can lead to a harsh or distorted audio output. To prevent or mitigate aliasing, techniques such as anti-aliasing filters are employed during the sampling process. These filters smooth out the signal before it is sampled, effectively removing high-frequency components that would otherwise cause aliasing. In computer graphics, anti-aliasing algorithms are applied during rendering to smooth out jagged edges and create a more visually pleasing image.